Age is the major determinant of recurrence in pediatric differentiated thyroid carcinoma.

BACKGROUND: A relationship between young age and increased risk of recurrence of pediatric differentiated thyroid carcinoma has been suggested; however, no attempts have been made to assess the prognostic factors or efficacy of treatment in very young children with this malignancy. The objectives of this study were to evaluate the association of age with outcome in pediatric differentiated thyroid carcinoma and to compare the clinical, pathologic, prognostic, and treatment variables between younger and older children with this disease.

PROCEDURE: A retrospective review of all patients presenting to the British Columbia's Children's Hospital or British Columbia Cancer Agency <17 years of age at diagnosis with differentiated thyroid carcinoma between January, 1955, and December, 1996, was completed.

RESULTS: Thirty-eight patients were identified, 12 of whom were </=10 years of age. The overall and relapse-free survivals at 20 years were 100% and 32.2%, respectively. Age at diagnosis was the only determinant of time to recurrence on univariate and multivariate regression analysis of prognostic factors (P = 0.022). The 20 year relapse-free survival for children < or =10 years of age was 10.1% vs. 48.3% for children >10 years. An association between young age and extrathyroidal tumor invasion was identified (P = 0.016); however, the latter factor did not independently predict outcome. There was a trend for suppressive doses of thyroid hormone to improve outcome, particularly with increasing age at diagnosis, but this was not statistically significant.

CONCLUSIONS: Age is the major determinant of recurrence in pediatric differentiated thyroid carcinoma. The results suggest different tumor biology in young children requiring novel approaches to therapy to decrease recurrence rates.